Lid opening/closing system for closed container, and substrate processing method using the same

ABSTRACT

The partial pressure of an oxidizing gas within a FOUP fixed to a FIMS system and placed in an open state is prevented from increasing with the lapse of time. To that end, a gas supply port is arranged in the bottom face of the FOUP to enable nitrogen supply into the FOUP through the gas supply port with a pod mounted on the FIMS system. A nitrogen supply system for supplying nitrogen with the FOUP mounted is controlled so as to make a nitrogen supply at such a low flow rate and pressure as to be able to prevent dust or the like having such sizes as to possibly cause problems in wiring lines to be formed on a wafer from being stirred up from the gas supply port or the like.

This application claims the benefit of Japanese Patent Application Nos.2012-264903 filed Dec. 4, 2012, 2013-129664 filed Jun. 20, 2013, U.S.provisional Application No. 61/842,600 filed Jul. 3, 2013 and JapanesePatent Application No. 2013-243838 filed Nov. 26, 2013, which are herebyincorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a so-called FIMS (Front-OpeningInterface Mechanical Standard) system used when wafers held in atransfer container referred to as a pod are transferred betweensemiconductor processing apparatuses in a semiconductor manufacturingprocess or the like. More specifically, the present invention relates toa FIMS system, namely, a lid opening/closing system, in which a podreferred to as a FOUP (Front-Opening Unified Pod) which is a closedcontainer for housing wafers is mounted and the lid of the pod isopened/closed to transfer wafers thereto/therefrom, and which includes apurge mechanism for purging the interior of the pod.

2. Description of the Related Art

Conventionally, a semiconductor manufacturing process has been carriedout in a so-called clean room in which semiconductor wafers are handledand the interior of which is highly cleaned up. From the viewpoint ofcoping with the increase of a wafer size and reducing costs required forthe management of the clean room, however, there has recently beenadopted a technique for keeping, in a highly clean state, only theinterior of a processing apparatus, a pod (wafer container), and minutespaces, i.e., minienvironment where wafers are transferred from the podto the processing apparatus.

The pod is comprised of a substantially cubic main body includingshelves capable of holding a plurality of wafers inside the pod with thewafers placed parallel to and separately from one another and anaperture formed in one of faces constituting the outer face of the podto take wafers in and out, and a lid for closing the aperture. The podin which the face where this aperture is formed is located on onelateral side (a face right opposite a minute space) of the pod, ratherthan in the bottom face thereof, is generically referred to as a FOUP(front-opening unified pod). The present invention is primarily directedat a system configuration using this FOUP.

The abovementioned minute space includes a first aperture facing theaperture of the pod, a door for closing the first aperture, an apertureprovided on the semiconductor processing apparatus side, and a transferrobot which steps into the pod from the first aperture to hold a waferand passes through the processing apparatus-side aperture to carry thewafer to the processing apparatus side. The system configuration havingthe minute space formed therein also includes a mounting stage forsupporting the pod so that the aperture of the pod faces the front ofthe door.

Positioning pins to be fitted into positioning holes provided in thebottom face of the pod to define the mounting position of the pod and aclamp unit to be engaged with a portion to be clamped provided in thebottom face of the pod to fix the pod onto the mounting stage arearranged on the top face of the mounting stage. Under normal conditions,the mounting stage can move back and forth over a predetermined distancein the direction of the door. When wafers inside the pod are transferredto the processing apparatus, the pod is moved, while being placed on themounting stage, until the lid of the pod comes into contact with thedoor. After the contact, the lid is removed from the aperture of the podby the door. By these operations, the interiors of the pod and theprocessing apparatus are communicated with each other through the minutespace. Thereafter, wafer transfer operation is performed repeatedly. Asystem including the mounting stage, the door, the first aperture, thedoor opening/closing mechanism, and walls constituting part of theminute space in which the first aperture is formed is genericallyreferred to as a FIMS (front-aperture interface mechanical standard)system.

Here, the interior of the pod in a state of containing wafers or thelike is generally filled with dry nitrogen or the like controlled to ahigh degree of cleanness, thereby preventing the ingress ofcontaminants, oxidizing gases and the like into the pod. When wafersinside the pod are taken into various types of processing apparatus toperform predetermined treatments on the wafers, however, the interiorsof the pod and the processing apparatus are constantly kept in a stateof being communicated with each other. A fan and a filter are disposedin the upper section of a chamber in which the transfer robot is locatedto introduce clean air, the particles and like of which are controlled,into the chamber. If such air goes into the pod, however, there arisesthe possibility that a wafer surface is oxidized due to oxygen ormoisture in the air. In addition, along with the miniaturization andperformance enhancement of semiconductor devices, attention is beingpaid to oxidization due to oxygen or the like getting inside the podwhich has been not so problematic before.

These oxidizing gases form ultrathin oxide films on various layersformed on a wafer surface or a surface of the wafer. Thus, there hasbeen the possibility of fine elements failing to have desiredperformance due to the presence of such oxide films. As acountermeasure, it is conceivable to prevent the ingress of gases, theoxygen partial pressure and the like of which are not controlled, intothe pod from the outside. As a specific method, Japanese PatentPublication Nos. 4301456 or 4309935 discloses a system configuration inwhich a nozzle for supplying an inert gas, such as nitrogen, is arrangedin a region adjacent to the aperture of a pod in a FIMS system. Theinert gas is supplied from the gas supply nozzle into the pod whoseaperture is opened by removing the lid of the pod, thereby reducingoxygen concentration within the pod. In addition, in a systemconfiguration disclosed in Japanese Patent Application Laid-Open No.2012-019046 or 2012-135355, an inert gas is supplied from a gas portprovided in a wall surface of a pod, thereby reducing oxygenconcentration. Yet additionally, Japanese Patent Application Laid-OpenNo. 2009-290102 discloses a system configuration in which an inert gasis supplied from both an aperture and a wall surface of a pod.

In the system configuration disclosed in Japanese Patent Publication No.4301456 or 4309935, a high-flow rate inert gas can be supplied using anaperture having a sufficiently wide frontage. Accordingly, an inert gasreplacement within the pod can be made promptly to easily reduce oxygenconcentration to or below a predetermined value. These systemconfigurations require opening the lid in order to make inert gasreplacement, however. Accordingly, oxygen concentration control during,for example, a standby time for the pod to wait for processing on themounting stage is virtually impossible. Here, a high-flow rate inert gassupply is not allowed from cost and safety points of view if, forexample, time taken to perform processing on a wafer alone is long. Itis thus conceivable to apply a mode of waiting ready with the pod closedby the lid all the time, except the time of taking in and out the wafer.At that time, oxygen concentration in the environment under which eachwafer immediately before processing is placed differs, if oxygenconcentration within the pod rises due to leakage or the like, ifultrafine wiring lines are formed, or if processing using highlyoxidative materials, gases and the like is performed. Accordingly, thecharacteristics of wafers may differ from one wafer to another. If thepod is increased in size to be compatible with large-diameter wafers, itis generally difficult to keep the internal space of the pod in anairtight state. Thus, there is concern that the leakage of internalgases or the ingress of external gases become increasingly likely tooccur during such a standby time.

In the case of the system configuration disclosed in Japanese PatentApplication Laid-Open No. 2012-019046 or 2012-135355, restrictions ariseon the diameter of a gas pipe to be used for inert gas supply since aport has to be provided on a wall surface of the pod. Consequently, inorder to supply an amount of inert gas for suitably lowering oxygenconcentration, the inert gas has to be supplied at a high flow rate.Since the pod has been increased in size as described above, however, itis increasingly difficult to secure a sufficient amount of inert gas tobe supplied. Even if a satisfactory supply of inert gas is possible, thepressure of the supplied gas has to be raised to increase the gas flowrate. This may cause dust or the like adhering to the vicinity of theport to be stirred up by the supplied gas, thus possibly contaminatingwafers. In the system configuration disclosed in Japanese PatentApplication Laid-Open No. 2009-290102, no consideration is given eitherto the above-described problems of rise in oxygen concentration duringthe standby time and to supply of a sufficient amount of inert gas.

The present invention has been accomplished in view of theabove-described background. Accordingly, an object of the presentinvention is to provide a lid opening/closing system configured toopen/close the lid of a pod which is a closed container and capable ofcontrolling the partial pressure of an oxidizing gas, such as oxygen,within the pod to a predetermined low level and maintaining this levelduring a so-called standby time.

SUMMARY OF THE INVENTION

In order to solve the above-described problems, a lid opening/closingsystem according to the present invention includes a container providedwith a substantially box-shaped main body capable of containing anobject to be housed and having an aperture in one face of the containermain body; a lid separable from the container main body and adapted tocover the aperture to form an enclosed space along with the containermain body; and at least one supply port provided on a wall surface ofthe container main body and capable of supplying a gas from the outside,wherein the object to be housed is allowed to be taken in and out of thecontainer by removing the lid from the container to open the aperture,the system including: a mounting stage on which the container is placed;a minute space located adjacent to the mounting stage to contain amechanism for transporting the object to be housed with particlescontrolled; a substantially rectangular first aperture formed in a walllocated adjacent to the mounting stage to define part of the minutespace, the first aperture being provided in a position where the firstaperture is able to face the aperture of the container placed on themounting stage; a door capable of holding the lid and substantiallyclosing the first aperture, and capable of causing the aperture and thefirst aperture to be communicated with each other by holding the lid andopening the first aperture; a supply valve for supplying a gas into thecontainer in conjunction with the supply port; and a gas supply systemfor supplying a predetermined gas through the supply port and the supplyvalve at a total flow rate of 1 to 60 L/min, or respective flow rate of1 to 20 L/min with the container placed on the mounting stage.

Note that the above-described lid opening/closing system preferablyincludes opening/closing detection means for detecting theopening/closing of the aperture by the door using the lid, and controlmeans for starting the supply of the predetermined gas to the gas supplysystem in response to the closure of the aperture detected by theopening/closing detection means. More preferably, the lidopening/closing system further includes a purge nozzle capable ofsupplying the predetermined gas to the container through the aperture ofthe container, and the control means performs the start and stop of thesupply of the predetermined gas by the purge nozzle in response to thedetection of the opening/closing of the lid by the detection means. Inaddition, the container may further include at least one discharge portprovided on a wall surface of the container main body and capable ofdischarging gases to the outside and the lid opening/closing system mayfurther include a discharge valve for discharging gases from within thecontainer in conjunction with the discharge port.

Alternatively, the above-described lid opening/closing system morepreferably includes: an enclosure arranged in the minute space in serieswith the first aperture to cover the moving space of the door andconstitute a second minute space, the enclosure having a second aperturethrough which the first aperture and the minute space communicate witheach other and the mechanism for transporting the object to be housed isallowed to pass along with the object to be housed; and a curtain nozzlelocated in a portion above the upper edge of the first aperture insidethe enclosure and capable of supplying the predetermined gas along adirection from the upper edge toward the lower edge of the firstaperture, wherein the enclosure more preferably includes a gas outletport from which the gas is allowed to flow out into the minute spacealong the direction in which the gas flows.

According to the present invention, it is possible to combine inert gasreplacement based on a large flow from the aperture and inert gasreplacement based on a small flow from a wall surface of the pod torapidly make inert gas replacement within the pod, and effectivelyprevent a rise in oxygen concentration also during a standby time or thelike with the pod placed on the mounting stage.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a schematic configuration ofprincipal parts of a lid opening/closing system according to oneembodiment of the present invention.

FIG. 2A is a schematic view illustrating a schematic configuration ofthe lid opening/closing system according to one embodiment of thepresent invention illustrated in FIG. 1, i.e., a load port, a pod, a lidfor the pod, and part of an opener, viewed from a cutting plane thereofperpendicular to the aperture of the pod.

FIG. 2B is a schematic view illustrating a state of a first aperture 10shown in FIG. 2A when viewed from the direction of arrows 2B.

FIG. 3 is a schematic view used to describe the direction of supply of apurge gas supplied from each purge nozzle into the pod.

FIG. 4A is a schematic view illustrating one step of operation toopen/close the lid in the lid opening/closing system illustrated in FIG.1.

FIG. 4B is another schematic view illustrating one step of operation toopen/close the lid in the lid opening/closing system illustrated in FIG.1.

FIG. 4C is a schematic view illustrating a state of the first aperture10 when viewed in the same manner as in FIG. 2B under the conditionshown in FIG. 4B.

FIG. 5 is an overall side view illustrating a schematic configuration ofa commonly-used semiconductor wafer processing apparatus to which thepresent invention is applied.

FIG. 6A is a schematic view illustrating a schematic configuration ofthe apparatus shown in FIG. 5 when a configuration of a dooropening/closing mechanism and the vicinity thereof is enlarged andviewed from a lateral side of the apparatus.

FIG. 6B is a schematic view illustrating a schematic configuration ofthe apparatus when the configuration shown in FIG. 6A is viewed from thetransfer chamber side.

FIG. 7 is a schematic view illustrating a vertical cross section of themounting stage, including a gas supply valve, in the lid opening/closingsystem illustrated in FIG. 1.

FIG. 8 is a schematic view illustrating another embodiment of thepresent invention and a schematic configuration thereof when aconfiguration of the top face of the mounting stage is viewed fromthereabove.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

FIG. 1 illustrates a schematic configuration of principal parts of a lidopening/closing apparatus (FIMS, which is hereinafter referred to as theload port) according to a first embodiment of the present invention.FIG. 1 is a schematic perspective view when only the abovementionedmounting stage, the door, the first aperture, part of the dooropening/closing mechanism, walls constituting part of the minute spacein which the first aperture is formed, the enclosure newly added in thepresent invention, and components associated therewith are viewed fromthe minute space side. FIG. 2A is a schematic view illustrating aschematic configuration of the cross sections of the load port and thepod, with the pod mounted on the load port (mounting stage) and the lidof the pod placed in abutment with the door. FIG. 2B illustrates a stateof a cross section along the line 2B-2B of FIG. 2A viewed from theminute space side. Note that various components associated with themounting stage and the like will be described later by referring to FIG.7.

Here, a description will first be made of the pod to be mounted on theload port and a wafer to be housed in the pod (see FIG. 2A). A space forcontaining a wafer 1, which is an object to be processed, in the pod isformed within a main body 2 a of the pod 2. The pod main body 2 a has asubstantially box-like shape having an aperture in one of faces presentin a horizontal direction. The pod 2 is provided with a lid 4 forhermetically closing the aperture 2 b of the pod main body 2 a. A rackhaving a plurality of selves (not illustrated) for vertically stackingwafers 1 horizontally held within the pod main body 2 a is arranged inthe pod. The wafers 1 placed on this rack are housed in the pod 2 whilebeing uniformly spaced. The wafers 1 correspond to the objects to behoused in the present invention, the pod 2 corresponds to the container,the pod main body 2 a corresponds to a pod main body defined as having asubstantially box-like shape since the basic shape of the pod main body2 a is boxy, and the aperture 2 b of the pod 2 corresponds to anaperture defined as being substantially rectangular since the basicshape of the aperture 2 b is rectangular. In addition, in the presentembodiment, the pod 2 includes a supply port 2 d for gas supply in thebottom face of the pod.

The load port 51 according to the present invention includes a mountingstage 53, a door 6, a first aperture 10 functioning as the aperture ofthe load port, a door opening/closing mechanism 60, a wall 11 which is amember for constituting a minute space (a transfer chamber 52 to bedescribed later) in which the first aperture is formed, and an enclosure31 newly added in the present invention. The mounting stage 53 includesa movable plate 54 having a flat surface in the upper portion thereof onwhich the pod 2 is actually mounted and capable of moving the mountedpod toward or away from the first aperture 10. Positioning pins 54 a areembedded in the flat surface of the movable plate 54. The positioningpins 54 a fit into positioning recesses 2 c provided in the bottom faceof the pod main body 2 a, thereby uniquely determining the positionalrelationship between the pod 2 and the movable plate 54.

In addition, the mounting stage 53 includes a gas supply valve 53 alocated on the front surface of the mounting stage, so as to enable thevalve to work in conjunction with a gas supply port 2 d provided in thebottom face of the pod 2 to supply a purge gas to the port. FIG. 7illustrates a vertical cross section of the mounting stage 53 includingthe gas supply valve 53 a. The gas supply valve 53 a is comprised of acheck valve capable of gas supply in one direction only. In the presentembodiment, the gas supply valve 53 a is arranged so as to form a pairin combination with the gas supply port 2 d provided in the bottom faceof the pod 2. An inert gas is supplied from an unillustrated inert gassupply system for controlling the pressure and flow rate of the gas tosupply or stop supplying the gas to the gas supply valve 53 a trough agas supply pipe 57. The gas supply valve 53 a is fixed to the mountingstage 53 through a valve up-and-down mechanism 55. The gas supply valve53 a is moved by the valve up-and-down mechanism 55 between a supplyposition where the valve can make an inert gas supply to the pod 2 and astandby position below the mounting stage where the valve does not makean inert gas supply and is prevented from contact with the bottom faceof the pod 2.

The first aperture 10 provided in the wall 11 is formed into such asize, i.e., a rectangular shape one size larger than the rectangularoutline of the lid 4, as to allow the lid 4 for closing the pod aperture2 b to fit into the first aperture 10 when the pod 2 positioned in placeon the movable plate 54 is brought closest to the first aperture 10 bythe plate. Note that the position at which the movable plate 54 stopsthe pod 2 may be any position where the door 6 can remove the lid 4 ofthe pod 2 from the pod main body 2 a. The door 6 is supported to a dooropening/closing mechanism 60 through a door arm 6 a. The dooropening/closing mechanism 60 allows the door 6 to move between aposition at which the door substantially closes the first aperture 10and a retreat position at which the door completely opens the aperture10 and an unillustrated transport mechanism can take each wafer 1 in andout of the pod 2 through the aperture 10.

The door opening/closing mechanism 60 is comprised of a plurality ofunillustrated air cylinders and the like and rotates the door 6 around afulcrum 61 in conjunction with the door arm 6 a. The rotationaloperation is performed between the closed position of the first aperture10 and a position at which the door 6 takes the posture of retreat whendriven vertically downward to the retreat position. A surface 6 b of thedoor 6 on the opposite side of a surface thereof opposed to the firstaperture 10 is formed into a rectangular flat surface having such a sizeas to enable a later-described second aperture 31 a to be closed. Theflat surface 6 b is inclined with respect to a surface for closing thefirst aperture 10. The angle of the inclination is set so as to beparallel to a surface in which the second aperture 31 a is formed, whenthe door 6 rotates to open the first aperture 10 and takes the postureof retreat. The door opening/closing mechanism 60 includes lidopening/closing detection means for sensing the attachment/detachment ofthe lid to/from the pod 2 by detecting the position of the door 6 andthe retention/non-retention of the lid 4 by the door 6.

The enclosure 31 is comprised of an upper edge-side straightening vane31 e and two lateral edge-side straightening vanes 31 f and 31 g and hasa rectangular solid shape whose one surface facing the wall 11 is anopen surface. The lateral length (length in the direction of a side ofthe first aperture 10 extending in the horizontal direction thereof,i.e., the width) of a space formed in the enclosure 31 is set so as toallow the enclosure to accommodate the door 6 and a later-describedcurtain nozzle 12. In addition, the longitudinal length (length in thedirection of a side of the first aperture 10 extending in the verticaldirection thereof) of the space is defined as the minimum length whichallows the enclosure to accommodate the door 6 even if the door 6 isplaced in either the retreat position or the closure position of thefirst aperture 10, and also accommodate the later-described purgenozzles 21 located in a portion outside the side edges of the firstaperture 10. Note that a reinforcing plate material may be locatedbetween the two lateral edge-side straightening vanes 31 f and 31 g tocouple these vanes together.

As a thickness (length in the operating direction of the movable plate54, i.e., a depth), the space has a length which prevents the flatsurface 6 b on the opposite of a surface of the door 6 on the firstaperture 10 side and the enclosure 31 from interfering with each other,and allows the flat surface 6 b to substantially close the secondaperture 31 a when the door 6 rotates around the fulcrum 61 to take theposture of retreat and stops at the time of opening the first aperture10. The enclosure 31 is located in a position best suited for theenclosure to accommodate the purge nozzles 21, the curtain nozzle 12 andthe door 6 and, along with the wall 11, forms a second minute space 30having a substantially rectangular solid shape.

A rectangular second aperture 31 a is formed in a surface of theenclosure 31 opposed to the first aperture 10. The second aperture 31 ais arranged oppositely to the first aperture 10. The rectangular shapeof the aperture preferably has such a minimum size as to prevent theenclosure 31 from interfering with the operation of an unillustratedtransport mechanism arranged in the minute space to take each wafer 1 inand out of the pod 2. This way of enclosure configuration is intended tobring the second minute space 30 within the enclosure 31 as close to theenclosed space as possible, and obtain a state in which the interiors ofthe space 30 and minute space 52 are substantially isolated from eachother. The side of the enclosure 31 facing in the retreat direction ofthe door 6 is open. A purge gas is supplied vertically downward from thelater-described purge nozzles 21 within the enclosure 31. Since a bottomface 31 b is open, a state of a so-called downflow being constantlyformed can be obtained also within the enclosure 31.

The curtain nozzle 12 is located in the uppermost portion of a space(the upper side of the upper edge of the first aperture) in the interiorof the enclosure 31 immediately before the first aperture 10. Thecurtain nozzle 12 is arranged in order to form a downflow inside thesecond minute space 30 and a gas curtain immediately before the firstaperture 10. In the present embodiment, the curtain nozzle 12 is locatedas close as possible to an upper end face 31 d (face opposed to theabovementioned bottom face 31 b) of the enclosure 31. The curtain nozzlehas a rectangular solid shape having upper and lower faces one sizesmaller than the upper end face 31 d. A plurality of nozzle apertures 12b is formed in a lower face 12 a of the curtain nozzle 12.

The purge nozzles 21 for supplying a purge gas to purge the interior ofthe pod 2 are also located inside the enclosure 31. Each purge nozzle 21includes a tubular purge nozzle main unit 21 a extending in onedirection and is connected to an unillustrated purge gas supply system.The purge nozzle main units 21 a are disposed in a pair and adjacentlyto outer sides of the two lateral edges of the aperture 10 on a side ofthe load port aperture 10 different from the side of the mounting stageon which the pod 2 is placed, so as to extend parallel to the lateraledges.

FIG. 3 illustrates a schematic configuration when the purge nozzle mainunits 21 a, the pod 2, the wafers 1 and the enclosure 31 are viewed fromthereabove. In each purge nozzle main unit 21 a, a plurality of purgenozzle apertures 21 b is preferably disposed at equal intervals in theextending direction thereof, so as to agree with an interval at whichthe wafers 1 are housed in the pod 2 and with a spacing betweenrespective wafers 1. In addition, the purge nozzle apertures 21 b areformed so as to be directed at the central part of each wafer 1. Thatis, the direction of gas supply from each purge nozzle is preferablyparallel to a plane extending perpendicularly to the direction of gassupply from the curtain nozzle and toward a point at an equal distancefrom the two purge nozzles within the plane.

The purge gas can be reliably supplied into the pod 2 by setting thedirection of gas supply from the purge nozzles perpendicularly to theflow direction of a curtain gas. Originally, the purge gas is mosteffectively ejected so as to head to a wafer surface. For such a reasonthat the wafers 1 are narrowly spaced within the pod 2, however, a gassupply is made parallel to the wafer surface. Note that in practice, thepurge nozzles 21 and the abovementioned curtain nozzle 12 are connectedto an unillustrated gas supply system. For ease of understanding theconfiguration of the present invention, however, the drawing shows thesenozzles without including the gas supply system. Also note that this gassupply system is a common system comprised of a gas source, a regulatorand the like, and therefore, will not be discussed here.

In the present embodiment, the nozzle apertures 12 b are formed overalmost the entire surface of the bottom face 12 a of the curtain nozzle12. Accordingly, a so-called downflow based on a curtain gas suppliedfrom the curtain nozzle 12 is constantly formed in the space between thefirst aperture 10 and the second aperture 31 a within the enclosure 31when the door 6 is in the retreat position. In a state of being incommunication with the interior of the pod 2, the second minute space 30is communicated with the minute space 52 by the second aperture 31 a,through-holes in the bottom face 31 b of the enclosure, and the like.That is, the bottom face 31 b of the enclosure serves as a gas outletport and an outflow path of the curtain gas. In the present invention,the gas outlet port is located in a position opposite to the flowdirection of the curtain gas and perpendicularly to the gas flow. Bylocating the outflow path of the curtain gas in the bottom face 31 b ofthe enclosure, it is possible to reliably extend the downflow up to thelower portion of the second minute space 30 in a stable state of flow.

In addition, the curtain gas is easier to control in terms of so-calledcontaminants, such as particles, than a gas (atmospheric air) suppliedinto the minute space 52 through a later-described fan filter unit.Accordingly, it is possible to more effectively prevent the inflow ofcontaminants from the minute space 52 side into the pod 2, compared witha conventional load port, by locating the curtain gas-based downflow ina position immediately before the first aperture 10.

Here, a so-called downflow 63 a based on clean air is formed in theminute space 52 by a fan filter unit (FFU) 63 located in the upperportion of the space, in order to maintain cleanness in the interior ofthe space at a high level. That is, the minute space 52 is placed underparticle control and used as a space where the transport mechanism isarranged. An unillustrated gas outflow path is provided in the lowerportion of the minute space 52. Pressure inside the minute space 52 iskept slightly higher than pressure in a space outside the minute space,however, by adjusting the amount of air blow of the fan filter unit 63.By adjusting the amount of curtain gas flowing out of the gas outflowpath communicated with the minute space 52 and the amounts of curtaingas and purge gas supplied from the curtain nozzle 12 and the purgenozzles 21, it is possible to easily create an environment in whichinternal pressure lowers in the order of the second minute space 30, theminute space 52 and the outer space.

Note that in practice, pressure differences among these spaces aremarginal. If, for example, the second minute space 30 is arranged in aspecific exhaust path and gases are discharged by the exhaust path, itis in fact difficult to provide such pressure differences. In thepresent invention, a path communicated with the minute space 52 in thelower portion of the space is used as a main path of gas outflow fromthe second minute space 30 serving as a gas outlet port by arranging acommunicating part in the downstream of a linear flow of purge gas.Thus, the exhaust resistance of the path is adjusted to an appropriatevalue to make it easy to create the abovementioned pressure differences.

In the present embodiment, the second aperture 31 a is arranged so thatthe direction in which the second aperture 31 a is open is parallel tothe direction of the downflow 63 a from the fan filter unit 63. Inaddition, the curtain nozzle 12 is arranged so that the flow directionof purge gas supplied from the curtain nozzle 12 is also parallel to thedirection in which the second aperture 31 a is open. Since the flow ofthe purge gas and the flow of the downflow 63 a are parallel to eachother and a slight flow velocity difference is kept therebetween fromthe viewpoint of maintaining a fine pressure difference, the action of aso-called venturi effect is marginal. Accordingly, atmospheric air drawnfrom the minute space 52 into the second minute space 30 by the venturieffect is kept to a small amount. On the other hand, gases presentwithin the pod 2 are inherently stationary, and therefore, largelydiffer in flow velocity from the curtain gas. Consequently, there can beexpected an effect of drawing out the gases inside the pod 2 to thesecond minute space 30 side by the venturi effect. The above-describedeffect, along with the supply of purge gas, enables purge operationwithin the pod 2 to be performed more efficiently.

It is conceivable that gases used during processing and attached towafer surfaces desorb therefrom to contaminate the minute space 52 when,for example, processed wafers are housed in the pod and taken in and outof the pod. In the present invention, the desorbed gases are driven outfrom the vicinity of the wafer surfaces by the purge gas and carried bythe curtain gas from the second minute space 30 to the minute space 52through the abovementioned gas outlet port. The gases can be carried outof the minute space 52 through an unillustrated exhaust part (formed inthe lower portion or bottom face of the minute space 52) for dischargingthe downflow 63a from within the minute space 52 to the outer space.Accordingly, the gases deriving from the wafers are driven out into theouter space through the second minute space which is narrow and high indownflow velocity, rather than from a minute space which is wide and lowin downflow velocity in a conventional system configuration, whileminimizing the time taken for the gases to go through the minute space.That is, the interior of the pod 2 containing the processed wafers canbe purged more efficiently by allowing the curtain gas and the purge gasflowing in different directions to be simultaneously present in the pod.

When a gas is supplied toward a specific space by a commonly-used nozzleor the like, gases in the vicinity of the nozzle get involved in the gasby the earlier-mentioned venturi effect. As a result, the purity of thegas supplied degrades from the time immediately after the gas isreleased from the nozzle or the like. In the present invention, a wallconstituting the enclosure 31 is located at the back of both the curtainnozzle 12 and the purge nozzles 21. Consequently, atmospheric air isunlikely to be supplied from outside the enclosure 31 to the vicinity ofthese nozzles. Thus, gases, other than a predetermined gas, present inthe vicinity of the nozzles can be reduced as much as possible byperforming gas release operation for a certain period of time. That is,it is also possible to supply gases kept at a high level of purity fromthe nozzles.

It is also an object of the present invention to prevent a rise in thepartial pressure of an oxidizing gas within the pod 2 in a so-calledstandby state in which the lid is fixed to the pod 2. In the presentembodiment, a high-flow rate supply of an inert gas from each purgenozzle 21 is primarily applied in so-called purge operation on theinterior of a commonly-used pod 2. The flow rate is, for example, 300L/min. With this flow rate, it is possible to decrease the partialpressure of the oxidizing gas within the pod 2 to or below apredetermined value in a short period of time. In the standby state, arise in the partial pressure of the oxidizing gas is attributable toinherently-unacceptable minor leakage or the like. There is therefore noneed for a supply of an inert gas at a high flow rate. In the presentembodiment, the inert gas is supplied through the gas supply valve 53 aand the gas supply port 2 d at a low flow rate of, for example, 1 to 60L/min, which is a total flow rate of the inert gas from all of the gassupply valves 53 a and the gas supply ports 2 d and at which it is lesslikely to stir up dust and the like having potentially problematic sizesfrom the valve or the port. Note that if, for example, the flow rate ofa gas supplied from each purge nozzle is high, the abovementioned lowflow rate may alternatively be set lower than this flow rate. Regardingthe above flow rate, a flow rate of the inert gas from one set of thegas supply valve 53 a and the gas supply port 2 d is preferably set to 1to 20 L/min. In a case of setting the gas flow rate from one set to 1 to20 L/min, the dust and the like stirred up by the gas flow in the areaon which the gas supply valve 53 a and the gas supply port 2 d, issuppressed or prevented.

With the flow rate mentioned above, it is possible to prevent a rise inthe partial pressure of an oxidizing gas by applying such a low flowvelocity at which dust can be prevented from being stirred up, even ifthe diameter of the gas supply pipe 57 is small. More specifically,since dust or the like having such sizes as to possibly cause problemsin wiring lines to be formed on a wafer will become problematic, controlis performed so as to make a nitrogen supply at such a low flow rate andpressure as to be able to prevent dust or the like having these sizesfrom being stirred up from the gas supply port 2 d or the like. In thepresent embodiment, the abovementioned flow rate is selected on thebasis of the above-described conditions and the minimum amount of gassupplied to maintain the interior of the pod 2 at a constant positivepressure (pressure higher than the pressure of the outer space) during astandby time.

Note that in the present embodiment, any significant effects cannot beexpected from inert gas supply from the abovementioned path in a stateof the lid 4 being removed. Instead, inert gas supply from the purgenozzles 21 is suitable. Accordingly, the present embodiment is intendedto make an inert gas supply at suitable points in time by unillustratedcontrol means. More specifically, the present embodiment is adapted sothat the closure of the aperture 2 b with the lid 4 is detected by theearlier-mentioned lid opening/closing detection means and then, inresponse, the control means allows the inert gas supply system to startinert gas supply. In the present embodiment, a mode of using only onecombination of constituent parts comprised of the gas supply valve 53 ais shown by way of example. As will be described later, however, thenumber of combinations may be increased according to the inner volume ofthe pod 2 or the required partial pressure of an oxidizing gas.Alternatively, it is also possible to configure the system of thepresent embodiment such that an exhaust port for discharging gaseswithin the pod 2 is newly added to further reduce the partial pressureof the oxidizing gas also during a standby time.

According to the present invention, it is possible to prevent a rise inthe partial pressure of an oxidizing gas by continuing gas supply fromthe port even under a sealed condition in which a gas within the podleaks even in a state of the lid thereof being closed, and the ingressof external gases is likely to occur. For example, a case is conceivablein which if the processing time of a wafer alone is long, the lid isclosed as appropriate to wait for the end of one cycle of processing ina standby state. Conventionally, the partial pressure of the oxidizinggas within the pod rises as the standby time is prolonged, andtherefore, wafer surface oxidation may progress. According to thepresent invention, however, the partial pressure of the oxidizing gas isconstantly kept to or below a predetermined value even if the standbystate is prolonged. Thus, there can be obtained an effect of maintainingthe quality of all of wafers within the pod.

By arranging a quasi-second minute space where not only particles butalso the partial pressure of the oxidizing gas is controlled between aminute space where particles are controlled but the partial pressure ofthe oxidizing gas is not controlled and the interior of the pod, it ispossible to more significantly suppress the amount of oxidizing gasdiffusing from the minute space to the pod, compared with a conventionalsystem configuration. In addition, the system is configured such thatthe second minute space and the minute space are communicated with eachother by a gas outlet port and gases within the second minute space flowout into the minute space according to the pressure difference betweenthese spaces. Yet additionally, an inert gas is supplied from a wallsurface of the pod thereinto. It is therefore possible to easilygenerate atmospheric pressure differences among the second minute space,the minute space, and the vicinity of the minute space with a simplesystem configuration. Consequently, it is possible to effectivelyprevent the diffusion of an oxidizing gas from the minute space into thepod.

In addition, a downflow based on a purge gas is created within thesecond minute space and a so-called gas curtain is formed by thedownflow. Consequently, it is possible to effectively prevent thediffusion of atmospheric air, the scatter of particles, and the likefrom the minute space toward the pod. Yet additionally, by combining theabovementioned effect and the above-described effect of generatingpressure differences, it is possible to obtain the same or higher effectof maintaining the low partial pressure of a oxidizing gas using a smallamount of purge gas, compared with a case in which a large amount ofpurge gas is required to prevent the ingress of an oxidizing gas intothe pod simply by supplying the purge gas into the pod or with aconventional system configuration in which a gas curtain is formed bysupplying a large amount of purge gas from one direction and suctioningand discharging the gas from another direction.

Note here that it is known that when a gas is ejected from a nozzle, thegas involves other gases present in the vicinity of a nozzle aperture toturn into a mixed gas, thus forming a gas flow. That is, as the resultof the gas involving other gases present in the vicinity of the nozzleaperture when a gas curtain is formed, the concentration of a purge gas,such as an inert gas, forming the gas curtain decreases. Thus, there isthe possibility of an oxidizing gas being supplied from the gas curtaininto the pod. According to the present invention, the small-volumesecond minute space substantially closed by the enclosure and the dooris filled to some degree with a purge gas using the gas curtain, andthen the purge gas is supplied from the purge nozzles different from thecurtain nozzle. Accordingly, even if the purge gas supplied from thepurge nozzles involves gases around the purge nozzles, it only meansthat the purge gas involves gases originally low in the partial pressureof an oxidizing gas. Thus, it is possible to prevent a degradation inthe purity of the purge gas.

In addition, the periphery of the curtain nozzle is also surrounded bythe enclosure and can therefore be also easily filled with a purge gashaving purity above a certain level. The same is true for the purgenozzles. The periphery of each purge nozzle is surrounded by theenclosure and can therefore be also easily filled with a purge gashaving purity above a certain level. By the effects described above, itis possible to also obtain an effect of keeping the partial pressure ofan oxidizing gas contained in gases introduced to the periphery of thepod lower than before.

Next, a description will be made of the operation of the above-describedsystem configuration when the wafer 1 is actually taken in and out ofthe pod 2. The door 6 substantially closes the first aperture 10 at thetime the pod 2 is placed on the mounting stage 53. Note that in thepresent embodiment, the door 6 is sized so as to form such a gaptherearound as to cause the minute space 52 and the outer space to becommunicated with each other when the door is in a position to close thefirst aperture 10. Accordingly, in the present embodiment, the door 6 isonly capable of approximately closing the first aperture 10. After theplacement of the pod 2, the movable plate 54 moves toward the firstaperture 10 and stops at a position to cause the lid 4 to abut on thedoor 6. The door 6 holds the lid 4 with an unillustrated engagingmechanism. Note here that from the time before the pod 2 is placed,downflows are constantly formed within the minute space 52 by means ofthe fan filter unit 63 and within the second minute space 30 by gassupply from the curtain nozzle 12.

As described above, the flat portion 6 b located at the back of the door6 is arranged at a tilt with respect to the flow of a gas forming a gascurtain, so as to come closer to the second aperture 31 a as the flatportion moves away from the curtain nozzle 12. In addition, the lowerend of the flat portion 6 b is positioned below the lower edge thereofconstituting the second aperture 31 a. The internal pressure of thesecond minute space 30 divided off by the enclosure 31 is made higherthan pressure inside the minute space 52 by gas supply from the gascurtain nozzle 12. The inflow of particles and the like from the minutespace 52 into the second minute space 30 is more effectively preventedby applying, in addition to the pressure difference, a systemconfiguration in which the inclined surface of the flat portion 6 bchanges the direction of the gas curtain and flows part thereof into theminute space 52.

Subsequently, the door opening/closing mechanism 60 rotates the door arm6 a around the fulcrum 61, causes the door 6 to take the posture ofretreat illustrated in FIG. 4A, and makes the pod 2 partially open tothe second minute space 30. Note that FIGS. 4A and 4B to be discussedlater illustrate states of the enclosure 31 when the periphery of theenclosure 31 is viewed from the lateral side thereof in the same way asin FIG. 2A. From this state of the system, purge gas supply from thepurge nozzle is initiated. The door opening/closing mechanism 60retreats the door 6 down to the retreat position which is the lowermostend within the enclosure 31, while allowing the door 6 to maintain thisposture of retreat. FIG. 4B illustrates a state of the door 6 beingplaced in the retreat position. In this state, the aperture 2 b of thepod 2 is made open, thereby enabling operation by an unillustratedtransport mechanism arranged in the minute space 52 to transfer thewafer 1 into the pod 2 through the second aperture 31 a.

FIG. 4C illustrates a schematic configuration in which the firstaperture 10 is viewed from the minute space 52 side in the same way asin FIG. 2B. A gas, such as a purge gas, is supplied from the curtainnozzle 12, so as to form a downflow parallel to the wall 11. Inaddition, the purge gas is supplied from each of a pair of the purgenozzles 21, so that the flow of each purge gas heads for the centralpart of the wafer 1 housed in the pod 2. Under the above-describedcondition, the wafer 1 is transferred. Purge operation on the interiorof the pod 2 is performed continuously during the transfer operation tokeep low the partial pressure of an oxidizing gas within the pod. Aftercarry-in operation on the wafer 1 to be housed in the pod 2 iscompleted, the closing operation of the lid 4 is performed as describedbelow.

In the closing operation, the door opening/closing mechanism 60 raisesand brings back the door 6 up to the position illustrated in FIG. 4Awhere the door 6 stopped rotating to take the posture of retreat. Underthis condition, the door opening/closing mechanism 60 stops operationonce and maintains the door 6 in that posture before its rotation. Atthat time, the flat surface 6 b located at the back of the door 6 comesinto substantially close contact with the periphery of the secondaperture 31 a of the enclosure 31, thereby increasing the degree ofclosure of the second minute space 30. In addition, the lid 4 held onthe door 6 is positioned at a certain flow angle with the gas curtain,thereby changing the direction of gas flow from downward from theenclosure toward the interior of the pod.

By an increase in the degree of closure of the enclosure 31, it ispossible to easily raise the partial pressure of a purge gas present ina space including the second minute space 30 and the inner space of thepod 2. In addition, purge efficiency within the pod 2 is furtherenhanced since the curtain gas can be directly used to purge theinterior of the pod 2. After the interior of the pod 2 is fully purgedand the amount of oxidizing gas present in the abovementioned space issufficiently reduced by maintaining the condition shown in FIG. 4A for apredetermined period of time, the door opening/closing mechanism 60rotates the door 6 and closes the aperture 2 b of the pod main body 2 awith the lid 4. By the operations described above, it is possible toenclose the wafer 1 in the pod 2 at such a low concentration of anoxidizing gas as is not available with a conventional configuration.

Subsequently, the lid opening/closing detection means detects theclosure of the aperture 2 b with the lid 4, and notifies this to thecontrol means. In response to the notification of the detection ofclosure, the control means instructs the inert gas supply system tosupply an inert gas. The inert gas supply system begins supplying aninert gas into the pod 2 through the gas supply valve 53 a and the gassupply port 2 d at a predetermined flow rate or flow velocity. Thecontrol means also instructs a mechanism for supplying an inert gas tothe purge nozzle 21 to lower the flow rate or stop inert gas supply.This operation prevents or suppresses unnecessary use of the inert gas.By performing the operations described above, it is possible to satisfyboth a decrease in the partial pressure of an oxidizing gas inside thepod 2 and the maintenance of that condition in an atmospheric statethrough the use of a necessary and sufficient amount of inert gas.

Note that in the above-described operations, the door 6 is kept beingretreated from the start to the end of carrying in and out the wafers,while the wafers are being taken in and out. Here, if an attempt is madeto promptly and effectively purge the interior of the pod 2, a largeamount of purge gas needs to be supplied into the space being purged toraise the pressure thereof and rapidly drive out gases previouslypresent therein. It is difficult, however, to extremely raise theinternal pressure of the second minute space 30 if the second aperture31 a is in an open state as in the above-described operation. Inaddition, if the open time is long, the partial pressure of an oxidizinggas within the pod 2 may conceivably increase gradually due to thediffusion of atmospheric air from the minute space 52. In such a case,it is desirable to purge the pod 2 by raising the door 6 from theretreat position to the position shown in FIG. 4A where the secondaperture 31 a is substantially closed, and placing the interiors of thesecond minute space 30 and the pod 2 in a substantially airtight stateeach time one wafer 1 is taken in and out. Consequently, it is possibleto effectively prevent a rise in the partial pressure of the oxidizinggas.

Note that in the embodiment described above, the curtain nozzle 12 has arectangular solid shape and gas ejection holes are arranged on theentire lower surface of the nozzle. It is desirable, however, to changethe shape, the layout and the number of ejection holes as appropriate,according to the flow rate of a gas to be supplied, the volume of thesecond minute space 30, and the like. It is also preferable to changethe shape, the layout and the like of the gas-ejecting apertures 21 b ofthe purge nozzles 21 as appropriate. Also note that in theabove-described embodiment, the door 6 substantially closes the firstaperture 10. Alternatively, the door 6 may be configured to completelyclose the first aperture 10. Also note that in the above-describedembodiment, the bottom face 31 b of the enclosure is made open to serveas a gas outlet port arranged oppositely to the flow direction of acurtain gas. Alternatively, the bottom face 31 b may have, for example,a mesh structure, a structure provided with certain slits, a structurecomprised of punched, perforated metal, or the like which does notdisturb the formation of a downflow and the operation of the door 6 andexhibits a certain degree of exhaust resistance.

From the viewpoint of preventing the generation of particles and thelike, the amount of rotation of the door 6 is determined so that wallsaround the second aperture 31 a of the enclosure 31 and the flat surface6 b come close to but not into contact with each other. More preferably,however, the space between the flat surface 6 b and the enclosure 31 issealed up when the interiors of both the second minute space 30 and thepod 2 are purged at the same time. In this case, the door 6 may have atwo-step range of rotation to differentiate the position of the door 6between purge operation and retreat, so that these constituentcomponents temporarily come into close contact with each other only atthe time of purge operation. Alternatively, a sealing member whichexpands or shrinks due to fluid introduction or discharge, for example,may be arranged in the outer circumference of the flat surface 6 b. Inthis case, the sealing member may be structured so that theabove-described degree of close contact can be achieved by expanding andbringing the member into close contact with the enclosure 31 only at thetime of purge operation, and the contact with the enclosure 31 can becanceled by shrinking the sealing member.

Next, a description will be made of other embodiments of the presentinvention. In the above-described embodiment, a system configuration hasbeen shown by way of example in which a gas supply is made from the gassupply valve 53 a located in the mounting stage 53 to the pod 2 throughthe supply port 2 d. In the present embodiment, not only a gas issupplied to the pod 2 but also the gas is discharged from within the pod2 in a state of being high in internal pressure due to the gas supply,thereby forming a flow of clean gas within the pod 2. Thus, the partialpressure of an oxidizing gas is lowered more effectively. FIG. 8 is oneexample of the present embodiment and illustrates gas supply valves 53 aand a gas exhaust valve 53 b arranged in the upper surface of a mountingstage 53. Note that in FIG. 8, a first aperture 10 is arranged above thefigure. In addition, these valves respectively have structuresconsistent with the structures illustrated by way of example in FIG. 7,and ports adapted respectively to use with these valves are alsoarranged in the bottom face of the pod 2. In the present embodiment, anexample is shown in which these valves are comprised of three gas supplyvalves 53 a and one gas exhaust valve 53 b.

In the present embodiment, gases are discharged from an unillustratedgas exhaust system to the gas exhaust valve 53 b through a gas exhaustpipe arranged in the same way as the gas supply pipe 57. It is alsopossible to exclude the gas exhaust system and discharge gases by takingadvantage of pressure within the pod 2. In addition, the control meansarranged in the earlier embodiment may operate the gas exhaust valve 53b according to the operation of the gas supply valves 53 a. In anotheraspect of the present embodiment, the gas exhaust valve 53 b may be aso-called differential pressure valve or the like, and the valve goesinto an open state at the moment the internal pressure of the pod 2exceeds a predetermined pressure. In order to prevent dust or the likefrom getting inside the gas supply pipe through the gas supply valves 53a, filters or the like may be arranged in the gas supply valves 53 a. Byarranging filters or the like in gas supply lines as described above, itis possible to avoid bringing dust into the pod 2 at the time ofsupplying an inert gas from the lines into the pod.

Note that various modifications can be made according to, for example, amode in which only some of these valves are used, a mode in which thenumber of valves is varied between supply and exhaust purposes, theinner volume of the pod 2, or the required partial pressure of anoxidizing gas. For example, it is possible to adopt a mode in which onevalve is used as a gas supply valve 53 a, another valve is used as a gasexhaust valve 53 b, and other two valves are not used. It is alsopossible to change the total number of valves and the layout thereof.For example, a mode is conceivable in which the number of valves itselfis increased to eight or the gas supply valve 53 a is positioned in thedeepest part of the pod 2 and located in immediate proximity to asidewall thereof. Yet additionally, in these embodiments, valves andports are located only in the bottom face of the pod 2 in considerationof compatibility with an existing load port apparatus. The same effectcan be obtained, however, even if some or all of the valves and portsare arranged on the lateral side, the upper surface, or the lid side ofthe pod 2.

In the above-described embodiment, a case is illustrated by way ofexample in which the amount of inert gas supplied from each purge nozzle21 is 300 L/min, and the total amount of the inert gas supplied of allof the gas supply valves 53 a is 1 to 60 L/min and amount of inert gassupplied from each gas supply valve 53 a is 1 to 20 L/min. In practice,however, an actual amount of the inert gas supplied from each purgenozzle 21 is controlled within a range from 60 to 300 L/min, accordingto a required inner volume of the pod, a required partial pressure of anoxidizing gas, and the like. Accordingly, the amount supplied is inpractice controlled within a range from 1 to 60 L/min according to theseconditions and to variations in the number of gas supply valves 53 a,the layout thereof, or the like as in the case of the presentembodiment. Taking into consideration the time required to decrease thepartial pressure of an oxidizing gas to or below a desired value, theamount of inert gas supplied through each gas supply valve 53 a shouldpreferably be as large as possible. Taking into consideration thestirring up of dust and the like due to gas supply, however, the amountshould preferably be as small as possible. In consideration of thecharacteristics of the above-described respective inert gas supplysystems, the amount of inert gas supplied from each gas supply valve 53a is most preferably controlled within a range from 1 to 45 L/min.

Note that in above described embodiment, is described a case where boththe inert gas supplied from the purge nozzle and the inert gas suppliedfrom the gas supply valve and the gas supply port are used. However, thepresent invention is not limited by the above described aspect. It ispreferable that the inert gas is not supplied from the purge nozzle butthe inert gas is only supplied from the gas supply valve and the gassupply port. In such aspect, an effect of suppressing the dust and thelike stirred up by the gas flow can be obtained by setting a flow rateof the inert gas from one unit of the gas supply valve and the gassupply port to 1 to 20 L/min, and setting the total flow rate of theinert gas from the gas supply valves and the gas supply ports to 1 to 60L/min. Further, by satisfying the both requirements of each inert gasflow of 1 to 20 L/min and total inert gas flow to 1 to 60 L/min, thestirring the dust and the like can be preferably suppressed. Note thatalthough the combination of the purge nozzle and the gas supply valveand the gas supply port improve the working efficiency of purgeoperation, in a case of considering the prevention of stirring up thedust and the like the inert gas supply from the gas supply valve and thegas supply port is mainly used o as to shorten the time required for thepurge operation and to suppress the influence of the dust and the likeeffectively.

EXAMPLE EMBODIMENT

Next, a description will be made of a FIMS system which is an actual lidopening/closing system and for which the present invention is carriedout, and a semiconductor wafer processing apparatus using the system.FIG. 5 is a schematic view illustrating a schematic configuration of asemiconductor wafer processing apparatus 50 compliant to a so-calledmini-environment method. The semiconductor wafer processing apparatus 50is comprised mainly of a load port unit (a FIMS system and a lidopening/closing apparatus) 51, a transfer chamber (minute space) 52, anda processing chamber 59. Interfaces among these respective componentparts are defined by a load port-side partition and cover 58 a and aprocessing chamber-side partition and cover 58 b. In the transferchamber 52 of the semiconductor wafer processing apparatus 50, an aerialflow (downflow) is generated from above to below the transfer chamber 52by a fan filter unit 63 arranged in the upper portion of the transferchamber 52, in order to drive out dust and maintain a high degree ofcleanness. In addition, a downflow exhaust path is provided in thebottom face of the transfer chamber 52. The above-described apparatusconfiguration causes dust to be constantly driven out downward.

A pod 2 which is a container for housing silicon wafers or the like(hereinafter simply referred to as wafers) is placed on a mounting stage53 of the load port unit 51. As described earlier, the interior of thetransfer chamber 52 is kept at a high degree of cleanness in order toprocess wafers 1. In addition, in the transport mechanism, a robot arm55, which can actually hold a wafer, is arranged within the transferchamber 52. By this robot arm 55, each wafer is transferred between theinteriors of the pod 2 and the processing chamber 59. In general,various types of mechanisms used to perform treatments, such asthin-film formation and thin-film processing, on a wafer surface or thelike are contained in the processing chamber 59. These constituent partsare not directly relevant to the present invention, however, andtherefore will not be discussed here.

As described above, the pod 2 is comprised of a box-shaped main body 2 ahaving a space for containing the wafer 1 which is an object to beprocessed and including an aperture in one of the faces of the pod, anda lid 4 for hermetically closing the aperture. A rack including aplurality of shelves to stack wafers 1 in one direction is arrangedwithin the main body 2 a. Wafers 1 to be placed on these shelves arehoused in the pod 2 while being regularly spaced. Note that in theexample shown here, the direction in which the wafers 1 are stacked isdefined as the vertical direction thereof. The aperture 10 and theabovementioned enclosure 31 are arranged on the load port unit 51 sideof the transfer chamber 52. The aperture 10 is located in a position toface the aperture of the pod 2 when the pod 2 is placed on the load portunit 51 so as to come close to the aperture 10. Note that the mainconfiguration of the enclosure 31, the door 6 and the like according tothe present invention will not be discussed and illustrated here forreasons that they have already described in the foregoing embodimentsand from the viewpoint of making the drawings in question easy tounderstand.

FIGS. 6A and 6B respectively illustrate an enlarged cross-sectional sideview of the door 6 and the door opening/closing mechanism 60 of theapparatus and a front view when these constituent parts are viewed fromthe transfer chamber 52 side. A fixing member 46 is attached to the door6, and the door 6 is pivotally coupled with one end of the door arm 6 athrough the fixing member 46. The other end of the door arm 6 a issupported to the leading end of a rod 37 which is part of an air-drivencylinder, through an axis 40, so as to be rotatable around the axis 40.

A through-hole is provided between the one and the other ends of thedoor arm 42. An unillustrated pin penetrates through the through-holeand a hole of the fixing member 39 fixed to a supporting member 60 of amovable unit 56 for raising/lowering constituent parts, such as the doorarm 42, for opening/closing the door, thereby forming a fulcrum 61.Accordingly, the door arm 42 can rotate around the fulcrum 61 inresponse to the cylinder-driven extension and contraction of the rod 37.The fulcrum 61 of the door arm 42 is fixed to the supporting member 60provided in the movable unit 56 capable of up-and-down movement.

When each wafer 1 is processed using these constituent parts, the pod 2is first placed on the mounting stage 53, so as to come close to theaperture 10 of the transfer chamber, and the lid 4 is held by the door6. Note that an unillustrated engaging mechanism and an unillustratedmechanism to be engaged are arranged on surfaces of the door 6 and thelid 4, respectively. These mechanisms operate with the surfaces of thelid 4 and the door 6 abutting on each other, thereby allowing the door 6to close the lid 4. When the rod of the cylinder is contracted underthis condition, the door arm 42 rotates around the fulcrum 61, so thatthe door 6 moves away from the first aperture 10. This operation causesthe door 6 to rotate along with the lid 4 and remove the lid 4 from thepod 2. Thereafter, the movable unit 56 is lowered to carry the lid 4 toa predetermined retreat position. This carrying operation has alreadybeen described in the foregoing embodiments, and therefore, will not bediscussed here.

Note that although the present example embodiment is described withFOUPs and FIMS systems as targets, applications of the present inventionare not limited to these. As far as a front open type container forcontaining a plurality of objects to be held and a system foropening/closing the lid of the container to take the objects to be heldin and out of the container are concerned, it is possible to apply a lidopening/closing apparatus according to the present invention to thecontainer and the system and keep low the partial pressure of anoxidizing atmosphere within the container. In cases where a specific gashaving desired properties, rather than an inert gas, is used as a gas tobe filled in the container, it is also possible to use the lidopening/closing apparatus according to the present invention to keep thepartial pressure of the specific gas within the container at a highlevel.

According to the present invention, there are obtained an effect ofshielding a space with an enclosure and an effect of preventing theingress of external gases from a gas curtain or the like due to purgegas supply. In addition, by supplying a purge gas toward a waferseparately from the gas curtain, it is possible to effectively suppressa rise in the partial pressure of an oxidizing gas among gases within apod. Yet additionally, the present invention can be carried out simplyby adding an enclosure, a curtain nozzle, a purge nozzle and the like toan existing FIMS system. Consequently, the present invention can beinexpensively, simply and conveniently applied to any standardizedsystems.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. A lid opening/closing system including acontainer, the container being provided with: a substantially box-shapedmain body capable of containing an object to be housed and having anaperture in one face of the container main body; a lid separable fromthe container main body and adapted to cover the aperture to form anenclosed space along with the container main body; and at least onesupply port provided on a wall surface of the container main body andcapable of supplying a gas from the outside, wherein the object to behoused is allowed to be taken in and out of the container by removingthe lid from the container to open the aperture, the system comprising:a mounting stage on which the container is placed; a minute spacelocated adjacent to the mounting stage to contain a mechanism fortransporting the object to be housed with particles controlled; asubstantially rectangular first aperture formed in a wall locatedadjacent to the mounting stage to define part of the minute space, thefirst aperture being provided in a position where the first aperture isable to face the aperture of the container placed on the mounting stage;a door capable of holding the lid and substantially closing the firstaperture, and capable of causing the aperture and the first aperture tobe communicated with each other by holding the lid and opening the firstaperture; a supply valve for supplying a gas into the container inconjunction with the supply port; and a gas supply system for supplyinga predetermined gas through the supply port and the supply valve at atotal flow rate of 1 to 60 L/min with the container placed on themounting stage.
 2. The lid opening/closing system according to claim 1,further comprising: opening/closing detection means for detecting theopening/closing of the aperture by the door using the lid; and controlmeans for starting the supply of the predetermined gas to the gas supplysystem in response to the closure of the aperture detected by theopening/closing detection means.
 3. The lid opening/closing systemaccording to claim 2, further comprising a purge nozzle capable ofsupplying the predetermined gas to the container through the aperture ofthe container, wherein the control means performs the start and stop ofthe supply of the predetermined gas by the purge nozzle in response tothe detection of the opening/closing of the lid by the detection means.4. The lid opening/closing system according to claim 1, wherein thecontainer further includes at least one discharge port provided on awall surface of the container main body and capable of discharging gasesto the outside, and the system further comprises a discharge valve fordischarging gases from within the container in conjunction with thedischarge port.
 5. The lid opening/closing system according to claim 1,further comprising: an enclosure arranged in the minute space in serieswith the first aperture to cover the moving space of the door andconstitute a second minute space, the enclosure having a second aperturethrough which the first aperture and the minute space communicate witheach other and the mechanism for transporting the object to be housed isallowed to pass along with the object to be housed; and a curtain nozzlelocated in a portion above the upper edge of the first aperture insidethe enclosure and capable of supplying the predetermined gas along adirection from the upper edge toward the lower edge of the firstaperture, wherein the enclosure includes a gas outlet port from whichthe gas is allowed to flow out into the minute space along a directionin which the gas flows.
 6. A lid opening/closing system including acontainer, the container being provided with: a substantially box-shapedmain body capable of containing an object to be housed and having anaperture in one face of the container main body; a lid separable fromthe container main body and adapted to cover the aperture to form anenclosed space along with the container main body; and a plurality ofsupply ports provided on a wall surface of the container main body andcapable of supplying a gas from the outside, wherein the object to behoused is allowed to be taken in and out of the container by removingthe lid from the container to open the aperture, the system comprising:a mounting stage on which the container is placed; a minute spacelocated adjacent to the mounting stage to contain a mechanism fortransporting the object to be housed with particles controlled; asubstantially rectangular first aperture formed in a wall locatedadjacent to the mounting stage to define part of the minute space, thefirst aperture being provided in a position where the first aperture isable to face the aperture of the container placed on the mounting stage;a door capable of holding the lid and substantially closing the firstaperture, and capable of causing the aperture and the first aperture tobe communicated with each other by holding the lid and opening the firstaperture; a plurality of supply valves for each supplying a gas into thecontainer in conjunction with each of the plurality of supply ports; anda gas supply system for supplying a predetermined gas through one unitof the supply port and the supply valve at a flow rate of 1 to 20 L/minwith the container placed on the mounting stage.
 7. The lidopening/closing system according to claim 6, further comprising:opening/closing detection means for detecting the opening/closing of theaperture by the door using the lid; and control means for starting thesupply of the predetermined gas to the gas supply system in response tothe closure of the aperture detected by the opening/closing detectionmeans.
 8. The lid opening/closing system according to claim 7, furthercomprising a purge nozzle capable of supplying the predetermined gas tothe container through the aperture of the container, wherein the controlmeans performs the start and stop of the supply of the predetermined gasby the purge nozzle in response to the detection of the opening/closingof the lid by the detection means.
 9. The lid opening/closing systemaccording to claim 6, wherein the container further includes at leastone discharge port provided on a wall surface of the container main bodyand capable of discharging gases to the outside, and the system furthercomprises a discharge valve for discharging gases from within thecontainer in conjunction with the discharge port.
 10. The lidopening/closing system according to claim 6, further comprising: anenclosure arranged in the minute space in series with the first apertureto cover the moving space of the door and constitute a second minutespace, the enclosure having a second aperture through which the firstaperture and the minute space communicate with each other and themechanism for transporting the object to be housed is allowed to passalong with the object to be housed; and a curtain nozzle located in aportion above the upper edge of the first aperture inside the enclosureand capable of supplying the predetermined gas along a direction fromthe upper edge toward the lower edge of the first aperture, wherein theenclosure includes a gas outlet port from which the gas is allowed toflow out into the minute space along a direction in which the gas flows.